Background: Malignant melanoma in childhood is rare. As a result, the biology and natural history of melanoma in this age group is still poorly understood. Although the majority of Spitz nevi are benign regardless of atypical features, a particular problem is the continued confusion of Spitz nevi with atypical features with melanoma and the lack of specific criteria for their distinction. The latter discrimination is perhaps not so difficult when Spitz nevi are minimally atypical; however, the greater the atypia, the more challenging is this discrimination.
Methods: All cases of malignant melanoma referred to Children's Hospital (Boston, MA) and to one of the authors were examined during the period of 1959-1995. Criteria for inclusion in the study included: (1) age up to 15 years; (2) availability of microscopic slides; and (3) availability of demographic data.
Results: There were 11 males and 12 females, ranging in age from 2 to 15 years (mean age, 9.4 years). Histopathologically, the 23 tumors were categorized into four subgroups: (1) small cell melanoma (5); (2) adult-like melanoma (6); (3) Spitz-like melanoma (3), and (4) atypical Spitz tumors (9). The small cell melanomas were notable for localization to the scalp, significant thickness, and fatal outcome. The adult-like melanomas resembled typical tumors occurring in adults. The one fatal Spitz-like melanoma was located on the neck of a 14-year-old male. Two tumors in this group metastasized to regional lymph nodes, but were not associated with further aggressive disease on follow-up despite treatment with surgical excision only. The atypical Spitz tumors were characterized by significant thickness and abnormal features including prominent cellularity and mitotic activity.
Conclusions: Anatomic site and cell type may be important prognostic factors in addition to tumor thickness for childhood melanoma, but these tumors require further study. In addition, the biologic potential of atypical Spitz tumors has not been characterized sufficiently.